| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To contrive coping with both of wide range luminance control including low luminance region and a high power efficiency. <P>SOLUTION: In a high luminance region wherein an objective luminance L is judged that the same is not less than a predetermined luminance value L0, an LED (light emitting diode) is driven by DC driving system by a constant current driving circuit. In the low luminance region wherein the objective luminance L is lower than the predetermined luminance value L0, the LED is driven by pulse width modulating driving system by a pulse width modulation driving circuit. Accordingly, luminance regulation through the pulse width modulation system is permitted in the low luminance region, and a high power efficiency can be maintained by the DC driving circuit in the high luminance region. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
